What to Reroll

Hey im currently thinking about rerolling for the next Season.since i have played a Holy Paladin the last 5 Seasons and im a bit tired of it. So i wanted a brief opinion on what is going to be strong next season I thought about rerolling a Shadow Priest, Rogue , Dk or maybe a Resto Shamy.
Im a bit affraid to go for a Caster since Rogues are going to be pretty strong.
So let me know what you think